How to improve the heat utilization efficiency of lime rotary kiln
Lime rotary kiln is the core equipment for lime production, and its heat utilization rate directly affects production costs and environmental benefits. Through multidimensional technological transformation and process optimization, the thermal efficiency of the system can be significantly improved.
Upgrading the combustion system is the core. By using energy-saving burners and matching them with intelligent air distribution systems, the fuel and air ratio can be dynamically adjusted according to the temperature and oxygen content inside the kiln, reducing incomplete combustion losses. For example, oxygen enriched combustion technology can increase flame temperature to over 1500 ℃ while reducing nitrogen oxide emissions. In the fuel pretreatment process, the coal powder preparation system is used to control the fuel particle size below 80 mesh, which can shorten the ignition time and improve the combustion rate.
The key is the cascade recovery of waste heat. Install a vertical preheater at the kiln tail to preheat limestone from room temperature to 850 ℃ using high-temperature flue gas, achieving a material pre decomposition rate of 30% and increasing system output by 40%. The vertical cooler at the kiln head uses the waste heat from the lime discharged from the kiln to preheat the secondary air to 600 ℃. Combined with a composite refractory lining (outer lightweight insulation, inner refractory wear-resistant), it reduces the heat dissipation of the kiln body and improves the overall thermal efficiency by 25%. Some enterprises adopt heat pipe flue gas water heat exchangers to convert exhaust waste heat into hot water for plant heating, achieving secondary energy utilization.
Optimization of process parameters is a guarantee. By installing distributed temperature sensors and PID control systems, precise control of the kiln temperature within ± 10 ℃ can be achieved. Extending the residence time of the material to 25-30 minutes, combined with the optimal calcination temperature range of 1200-1250 ℃, can ensure complete decomposition of calcium carbonate. The inclination angle of the kiln body is optimized to 3.5% -4%, combined with frequency conversion speed control technology, to achieve dynamic balance between the axial movement speed of the material and the heat exchange efficiency.
The coordinated implementation of the above measures can reduce the energy consumption per unit product of lime rotary kilns by 30% -40%, while reducing carbon dioxide emissions by 15% -20%, which meets the requirements of industrial green transformation.
